Prior attempts to prepare magnetic nanocomposites have utilized ground or milled particles of magnetic materials which were then dispersed in a carrier matrix, coated onto fabrics or added to finely ground, dispersed resins or zeolites. For example, Forder, et al. (“Preparation and Characterization of Superparamagnetic Conductive Polyester Textile Composites”, J. Mater. Chem., 3 (6) pp 563-569 (1992)) describes the preparation of magnetic colloids which are then coated onto the surface of a polyester fabric. Zhang, et al. (“Generation of Magnetic Metal Particles in Zeolite by Borohydride Reduction at Ambient Temperature”, J. Mater. Chem., 6(6) pp 999-1004 (1996)) treats sodium mordenite, a form of the naturally occurring zeolite designated hydrated calcium sodium potassium aluminum silicate, with a water soluble salt of a metal, M2+, where M is iron, cobalt or nickel, to replace Na+ on the resin with the metal ion. An aqueous suspension of the resin is then reacted with NaBH4 to reduce the metal ion to the metal M, which remains within the resin particles.
Ziolo, et al., (Ziolo, R. F., E. P. Giannelis, B. A. Weinstein, M. P. O'Horo, B. N. Ganguly, V. Mehrotra, M. W. Russell, and D. R. Huffman, “Matrix mediated synthesis of Fe2O3: A new optically transparent magnetic material”, Science 257:219-23 (1992)), reported on the preparation of Fe2O3 nanoparticles in sulfonated polystyrene-type 50-100 micron beads of ion exchange resin. They then had to be molded into monolithic structures at temperatures which modify the properties and characteristics of the nanoparticles. Sourty, et al., (“Ferrite-LoadED Membranes of Microfibrillar Bacterial Cellulose Prepared by in situ Precipitation”, E. Sourty, D. H. Ryan and R. H. Marchessault, Chem. Mater., 10(7), 1755-7(1998)) and Raymond, et al., (“In Situ Synthesis of Ferrites in Cellulosics,” L. Raymond, J.-F. Revol, D. H. Ryan, R. H. Marchessault; Chem. Mater.; 6(2); 249-255 (1994)) describe the formation of ferrites in cellulosics. Suber, et al. (“Synthesis, and Structural and Morphological Characterization of Iron oxide-Ion-Exchange Resin and-Cellulose Nanocomposites”, Applied Organometallic Chemistry, 15, 414-420 (2001)) reports on further studies of such materials. Shahinpoor, et al. reports on the treatment of ion exchange resins, such as Nafion with platinum salts to deposit platinum on or in the matrix (“Ionic Polymer-Metal Composites: I. Fundamentals,” Smart Mater. Struct., 10, 819-833 (2001).
Several patents have subsequently issued to Ziolo directed to magnetic nanocomposite compositions and processes for preparing these materials (U.S. Pat. No. 4,474,866, U.S. Pat. No. 5,714,536 and U.S. Pat. No. 6,148,920). In particular, these patents are directed to magnetic nanocomposite compositions containing nanocrystalline Fe3O4 particles formed in and stabilized by an ion binding polymeric matrix. In particular, granules of ion exchange polymer resin are suspended in a liquid and are then loaded with iron ions. The iron ions are then chemically converted to a magnetic oxide. For example, polystyrene-(SO3−)2Fe+2 resin is reacted with NaOH and H2O2 or N2H4 and NaOH to yield polystyrene-(SO3−Na+)n plus gamma Fe2O3, the oxide being dispersed in the polymer matrix with particle sizes from about 0.0001 to about 0.1 microns in diameter. The end product is a very fine powder of the resin including the magnetic oxide for use as a toner for reprographic application.
Treatment of oxides with sodium borohydride has been used since the early '70s to produce the oxide of the metal and to form nanoparticles. However, they were not called “nanoparticles” at that time. (W. O. Freitag, T. A. Sharp, A. Baltz, and V. Suchodolski, J. Appl. Phys., 50, pp. 7801-3 (1979), “Composition of iron powders prepared by a borohydride process,” and T. Uehori, A. Hosaka, Y. Tokuoka, and Y. Imaoka, IEEE Trans. Magn. 14, pp. 852-4 (1978) “Magnetic Properties of iron-cobalt alloy particles for magnetic recording media.”). The W. O. Freitag article points out that borohydride reduction methods have been well established, though not necessarily for nanoparticle alloys. Further, the nanoparticle alloys were not dispersed within the polymer structure.
U.S. Pat. No. 6,107,233 to Harmer is directed to the formation of spherically shaped porous microcomposites of perfluorinated ion-exchange resins with inorganic oxides dispersed starting there though from a mixture of a water miscible inorganic oxide and a water miscible ion-exchange resin. The mixture is then mixed with an organic liquid in which neither of the oxide or resin is soluble to create a dispersion of the water-miscible phase, in the form of spherical bubbles throughout the organic phase, followed by gelation of the water miscible components into spherical particles.
In general, nanomaterials can be fabricated with magnetic, magnetostrictive, or magneto-optic functionality. Phosphorescent nanocomposites have also been synthesized using the same technique. The nanocomposites can provide improved materials for various applications such as—                a. magnetics for power converters        b. actuators for artificial muscles, valves, micro-mirrors and micropumps        c. magneto-optical wave guides and switches        d. magnetics for guiding micro-catheters and for drug delivery        e. magnetodielectric materials for microwave and RF devices        f. applications requiring functional conformable materials, controlled displacement or positioning devices including macro and micro devices.        